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copied!<p>No, it is not.</p> <ul> <li><p>Objects are always automatically passed as references (<strong>info!</strong> see below for additional important information!)</p></li> <li><p>Declaring paramters as references must happen at the function definition:</p> <pre><code>function test(&$var) {} </code></pre> <p><strong>Not</strong> at the time of calling it:</p> <pre><code>// wrong $var = '123'; test(&$var); </code></pre></li> </ul> <p><hr /> If you pass an object as usual, you can alter the object's state (properties). <br /> Assume that <code>$obj</code> is an instance of the class <code>TestClass</code> which contains a member variable called <code>hello</code> (<a href="http://ideone.com/4mzU3P" rel="nofollow">click here for a full sample at Ideone.com</a>):</p> <pre><code>function modify($obj) { $obj->hello = 'world (modified)!'; } $obj->hello = 'world'; modify($obj); var_dump($obj->hello); // outputs "world (modified!)" </code></pre> <p>This should be self-explanatory. Now, using the same code but assigning another value to <code>$obj</code> instead modifying the object's state results in no modification (<a href="http://ideone.com/KopB7N" rel="nofollow">→ Ideone.com</a>):</p> <pre><code>function modify($obj) { $obj = 42; } // ... var_dump($obj->hello); // outputs "world" </code></pre> <p>Only accepting the parameter explicitly as a reference gives us the ability to completely change the variable's contents (<a href="http://ideone.com/XbFu7W" rel="nofollow">→ Ideone.com</a>):</p> <pre><code>function modify(&$obj) { $obj = 42; } // ... var_dump($obj); // outputs "42" </code></pre>

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